Primary secondary and tertiary wastewater treatment pdf

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primary secondary and tertiary wastewater treatment pdf

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Biological and Chemical Wastewater Treatment Processes

Enteric viruses, generally found in sewage, are recognized as the main cause of waterborne and foodborne public health outbreaks. Among leading enteric viruses, the Rotavirus A RVA detection in wastewater appeared to be a novel approach to monitor the emergence of these viruses in some countries where the viral gastroenteritis surveillance is almost absent such as in Tunisia. The RVA detection and quantification in an industrial sewage purification plant of Charguia I Tunis, Tunisia were achieved to evaluate the performance of activated sludge procedures coupled to a macrofiltration monolamp ultraviolet irradiation type C UV-C disinfection reactor.

A total of composite sewage samples was collected from this line of treatment and analyzed for RVA detection. It means that all wastewater sampled at this last step of treatment was positive for RVA detection.

On the other hand, However, the RVA quantification results expressed as viral load showed a significant reduction in the means of RVA viral loads at the exit of the biological activated sludge procedure and the tertiary UV-C treatment, showing in general an improved treated wastewater virological quality. In addition, good physical-chemical and bacteriological qualities of the treated sewage were found at the exit of the two considered wastewater treatment procedures.

The present investigation represents the first Tunisian environmental report showing the good effectiveness and performance of the biological and the tertiary treatments for RVA removal. Therefore, an improved and an optimized tertiary disinfection treatment was needed since it could be a good means for getting better viral water quality and for minimizing the transmission and dissemination of human infectious viral diseases. RVA are small non-enveloped viruses, with an icosahedral capsid Jayaram et al.

The RVA genome is composed of ten double-stranded, positive sense, mono-cistronic RNA molecules and one double-stranded polycistronic RNA molecule coding for structural and non-structural proteins Jayaram et al.

This group of viruses is divided into many serotypes based on the antigenic reactivity of the two-capsid structural proteins VP7 and VP4. The major glycoprotein VP7 and the minor protein VP4 encoded by gene 9, which defines 28 serotypes G G1—G28 and by segment 4, that describes 39 serotypes P P[1]-P[39] ,respectively Matthijnssens et al.

The RVA is considered the first pathogenic etiological agent of acute viral gastroenteritis in pediatric populations Murray et al. These viruses were recognized for their high genetic and antigenic assortment and diversity that are responsible of the emergence of some new genotypes every year Trask et al. In different countries in the world, RVA was detected with significant rates in sewage samples collected in dissimilar wastewater treatment plants Prevost et al.

Thus, these viruses are considered emerging enteric viruses in aquatic environments. The monitoring of wastewater treatment plants is a suitable approach to study the RVA circulation at these particular sites. This allows for a better understanding of the molecular epidemiology of these viruses in children.

In addition, the RVA are detected in various sewage purification plants and the resistance of these viruses to different wastewater treatment procedures in many countries such as France, Iran, Italy, Germany, Brazil, Tunisia, Egypt, Venezuela, China, and Nigeria Rodriguez-Diaz et al. The main objective of the present study was to improve the existing limited data on RVA detection rates and viral load values in sewage in Tunisia and to evaluate the performance of biological and tertiary wastewater treatment procedures for the removal of this type of gastroenteric virus from wastewater.

This investigation, which has been conducted at the scale of a big industrial wastewater treatment plant of Charguia I 20, million cubic meters of treated wastewater per year , is considered the first study of its scale ever accomplished in Tunisia.

The present work was achieved at the scale of a big industrial sewage purification plant positioned in the business and residential region of Charguia I of Tunis City, northern Tunisia. The supplied wastewater is of different types such as domestic, hospital, urban, rain, and industrial coming from various areas of the great Tunis. The wastewater treatment plant Charguia I comprises successively four different treatment categories: the pre-treatment, the primary, the secondary or biological, and the tertiary wastewater treatment procedures Fig.

Finally, the tertiary treatment was achieved by using a UV-C monolamp disinfection reactor. The sewage to be purified circulates in the annular space between the quartz sheath and the inner wall of the irradiation chamber. A second passage of treated wastewater trough UV-C radiation is applied after a first one. Thus, treated wastewater passes twice through the irradiation chamber in order to raise the yield of the UV disinfection.

The schematic plan of the industrial wastewater treatment plant Charguia I coupled with the UV-C disinfection reactor is illustrated in Fig. The schematic plan of the industrial wastewater treatment plant of Charguia I and the schematic disinfection UV-C monolamp reactor. Throughout the 10 months of the present study from June to April , a total of wastewater samples has been collected at various seasons and in the different sampling campaigns at the scale of the industrial Charguia I.

Thus, at least seven sewage samples were collected every month as indicated: one sample at the entrance of wastewater treatment plant WWTP or raw wastewater RW , one at the exit of primary treatment OPT , one at the exit of activated sludge procedures OAS , one at the exit of secondary treatment OST , one sample at the exit of seeding sludge SS , and at last, two samples after the first and the second passages through the UV-C irradiation chamber of the disinfection pilot reactor UV P1 , UV P2.

As the last step, all treated wastewater mentioned as effluent of the plant will be stored in a big storage basin and the effluent will be canalized to the sea through a canal designed for this cause. This marine point of rejection of treated wastewater will be in the near future the subject of a follow-up study similar to the present study. The different sampling sites of wastewater were indicated and the monthly distribution of wastewater samples was shown in Fig.

The viral particles decontamination and precipitation were achieved using syringe filters 0. The final volume, after the last step of viral particle concentration, was around 2 mL. In every reaction, a series of dilutions 10 0 to 10 9 was added in the RVA amplification and quantification that is obligatory for the measurement of the RVA viral load in sewage samples.

A series of decimal dilutions ranging from 10 0 to 10 9 were prepared from this plasmid. It is important to note at the beginning of this paragraph that all the results obtained in this study were based on treatment effects by recording only the number of positive wastewater samples for rotavirus detection.

Thus, the presence of infectious or non-infectious viral particles active or not does not arise since we have used only the RVA real-time RT-PCR technique only technique available in our laboratory , which cannot differentiate between infectious and inactivated viral particles present in the wastewater. In fact, in this work, we measure only and strictly the effect of the treatment stage by only determining the presence or the absence of rotaviruses. Thus, a result in this study indicating a positive water sample for rotaviruses does not necessarily mean the presence of infectious particles; it can only be the simultaneous presence of both types of viral particles inactivated and live virus particles.

The RVA results showed that RVA were detected with higher and more significant frequencies in both raw wastewater RW and at the exit of the primary treatment OPT than those registered in the last three lagoon basins, such as the exit of activated sludge OAS , the seeding sludge SS and the exit of secondary treatment OST of the activated sludge procedure. Indeed, the average RVA load has oscillated between 1. However, the RVA median viral loads have varied between 1.

Similarly, the RVA detection rates were very high in the last three basins of activated sludge procedures and at the exit of the two successive UV-C passages.

These average loads were, respectively 5. Consequently, the RVA load results in the three categories of treatment adopted in this study primary, secondary, and tertiary showed in general a significant reduction of the RVA average loads from the upstream to downstream of the activated sludge procedure, and at the exit of the two-successive UV-C passages.

Rotaviruses A mean viral load in the inflows and outflows of the activated sludge procedure and in the purified effluents by the UV-C disinfection treatment. The physical-chemical and bacteriological results in the present study demonstrated a substantial decrease of the median values of the main parameters tested from upstream to downstream of the studied biological wastewater treatment procedure of WWTP Charguia I. In fact, the mean values of the major physical-chemical parameters studied decreased from to Moreover, the concentrations of the fecal bacteria reduced from 8.

The tertiary treatment results showed a substantial reduction of the median concentration of these fecal bacteria after the two successive passages through the UV-C reactor.

Therefore, these findings showed the effectiveness and the performance of UV-C monolamp disinfection reactors intended for the fecal bacteria reduction.

The obtained results of the RVA mean viral loads were used to assess the seasonality distribution of this type of enteric viruses in the wastewater samples collected from WWTP Charguia I during the 10 months of study from June to April The monthly distribution of RVA frequencies showed that these viruses were detected continuously in circulated sewage with an alkaline pH 7. However, the RVA quantification results demonstrated that these viruses were detected with low to moderate average frequencies during the dry period June to November months and with some significant median viral frequencies during the rainy period December to March months , thus recording an important peak during winter and spring Table 2 ; Fig.

The average viral load of RVA has oscillated between 1. Nevertheless, the median RVA load has fluctuated between 3. In addition, RVA was encountered along the four seasons with a notable peak during winter and spring in the first two basins RW and OPT of the activated sludge procedure. The monthly distribution of the rotaviruses A mean viral load in the inflows and outflows of the activated sludge procedure and in the purified effluents by the UV-C disinfection treatment.

The primary environmental study conducted by Ibrahim et al. Consequently, the results of this study let to show a significant increase of the RVA detection frequency in the wastewater draining in this same area of study. The important increase of RVA detection rates recorded in the two studies indicated the general emergence, development, and diffusion of this type of gastroenteric viruses commonly dispersed in sewage in the region of the city of Tunis.

These last two frequencies have been registered in wastewater samples collected at the scale of three different WWTP situated in the touristic area of Monastir, Sahel region of Tunisia Sdiri-Loulizi et al.

Therefore, these data also showed the substantial increase of RVA frequency between the two different regions. The important increase of RVA detection frequencies recorded in the three Tunisian environmental studies indicated and agreed on the effect the emergence and the diffusion of these types of gastroenteric virus in the sewage of Tunis and Monastir areas.

The emergence and the great diffusion of this type of gastroenteric viruses in Tunisian wastewater is conditioned and related to many various factors associated with the social, hygienic, and geographical dissimilarities of each contact population.

Furthermore, the RVA detection rates recorded in the present work were similar to those reported in earlier and original environmental studies achieved in contaminated wastewater sampled from different wastewater treatment plants in diverse regions of the world. Many other environmental reports demonstrated that RVA frequencies were around of In Brazil, the RVA detection rates oscillated between Therefore, the high RVA frequency rate confirmed that these viruses are recognized as emergent gastroenteric viruses in numerous natural aquatic environments and could be useful for the vaccine-monitoring program, the waterborne and foodborne disease prevention related with acute viral gastroenteritis.

These average loads were around 5. This first Tunisian environmental study in the northern area of Tunisia reported that the RVA quantification loads were on average more and less low to moderate from the first to the last basins of natural lagoon procedures and at the exit of a rotating biodisks process in a pilot WWTP. Therefore, these data indicated an important average viral load of RVA circulating in the sewage in this area of the city of Tunis.

Consequently, the important RVA average viral load of around 5. Subsequently, these findings established that sewage monitoring constitutes an original approach for the waterborne prevention and anticipation of viral pandemic gastroenteritis.

In addition, these last findings were dissimilar from those described in many environmental studies conducted in various countries of the world such as France, Brazil, Egypt, China, and Uganda Prevost et al.

In fact, in all these environmental studies, the recorded average viral loads of RVA were much higher than the ones registered in the present study. The RVA detection and quantification at the input and at the output of the three different wastewater treatment procedures primary decantation, activated sludge, UV-C are conducted in the WWTP Charguia I for the determination and the evaluation of the performance of these purification procedures in removing this type of virus.

Thus, the results of RVA quantification in the present study showed a significant decrease of the average viral load of RVA in the treated wastewater by activated sludge and UV-C procedures.

The RVA average viral loads declined from 5. In addition, the RVA average viral loads showed a moderate reduction from 5. Therefore, the RVA detection results showed no significant difference in the frequencies of these viruses registered in the different basins of the activated sludge and after the two successive passages through UV-C treatment procedures.

Thus, the biological appeared as more efficient and effective concerning the reduction of the average viral load as compared to the one determined in the case of the second step of UV-C According to these last results obtained and mentioned above, it appeared that wastewater treatment by activated sludge was more effective than the tertiary treatment using the disinfection UV-C system concerning the abatement of the viral particles.

Indeed, the treatment by disinfection is in general a complementary treatment and it is not necessarily more efficient than the one obtained by the activated sludge process. The intrinsic biophysicochemical conditions of wastewater are an important and decisive factor in the determination of the output of disinfection.

Thus, these conditions are, in general, more stressing for the survival and the maintenance of viral particles in charged water than in clear water. In the same way, there would be many viral particles that would be eliminated following their adsorption to the various suspended matter and solids and they would be eliminated during the process of primary and secondary wastewater settling or clarification.

Therefore, these data established an improvement of the virological quality of the purified effluents intended for recycling, agriculture reuse, and discharges into natural aquatic receiving environments. Consequently, the epidemiology monitoring systems of RVA circulating in polluted wastewater will be advantageous for the improvement of the virological quality of purified effluents.

In addition, the obtained results in the present research work represent the first Tunisian environmental report showing the performance of the biological activated sludge procedures , and particularly tertiary sewage purification procedures UV-C disinfection for RVA removal. These findings were similar to earlier first two Tunisian environmental reports conducted at the pilot WWTP El Menzeh I situated in the same area of the present study, north of Tunisia.

These last two studies showed a moderate effectiveness of two biological or secondary sewage purification procedures: rotating biodisks and natural lagoons for Noroviruses GII and RVA removal. Moreover, a recent Egyptian environmental study reported by El-Senousy and Abou-Elela demonstrated the effectiveness of two biological wastewater treatment procedures: anaerobic sludge blanket UASB and biological aerated filters BAF for enteric virus removal such as rotaviruses, noroviruses GI, GII, adenoviruses, and hepatitis E viruses.

Primary, Secondary, and Tertiary Wastewater Treatment: How Do They Work?

When wastewater arrives at the treatment plant, it contains many solids that cannot be removed by the wastewater treatment process. This can include rags, paper, wood, food particles, egg shells, plastic, and even toys and money. To remove these solids, the wastewater enters a building called the Headworks and passes through large screen filters which removed this material. The solids are then placed in a dumpster and taken to the landfill. This is the only byproduct of wastewater treatment that is not recycled! From the Headworks, the wastewater flows into two huge circular tanks called Primary Clarifiers. These tanks can hold , gallons of water each.

Tertiary treatment is the final cleaning process that improves wastewater quality before it is reused, recycled or discharged to the environment. The treatment removes remaining inorganic compounds , and substances, such as the nitrogen and phosphorus. Bacteria, viruses and parasites, which are harmful to public health, are also removed at this stage. Wastewater flows from the biological reactor and IDAL to a pumping station and meet in the flash mixer. Alum is used to help remove additional phosphorus particles and group the remaining solids together for easy removal in the filters.

Jun 27, Bloganica. In fact, there are three distinct steps involved in traditional wastewater treatment methods. Primary treatment of wastewater involves sedimentation of solid waste within the water. This is done after filtering out larger contaminants within the water. Wastewater is passed through several tanks and filters that separate water from contaminants. Secondary treatment of wastewater makes use of oxidation to further purify wastewater. This can be done in one of three ways:.

Sewage treatment

Sewage treatment is the process of removing contaminants from municipal wastewater , containing mainly household sewage plus some industrial wastewater. Physical, chemical, and biological processes are used to remove contaminants and produce treated wastewater or treated effluent that is safe enough for release into the environment. A by-product of sewage treatment is a semi-solid waste or slurry, called sewage sludge. The sludge has to undergo further treatment before being suitable for disposal or application to land.

Enteric viruses, generally found in sewage, are recognized as the main cause of waterborne and foodborne public health outbreaks. Among leading enteric viruses, the Rotavirus A RVA detection in wastewater appeared to be a novel approach to monitor the emergence of these viruses in some countries where the viral gastroenteritis surveillance is almost absent such as in Tunisia. The RVA detection and quantification in an industrial sewage purification plant of Charguia I Tunis, Tunisia were achieved to evaluate the performance of activated sludge procedures coupled to a macrofiltration monolamp ultraviolet irradiation type C UV-C disinfection reactor.

Secondary Wastewater Treatment

Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. If you continue browsing the site, you agree to the use of cookies on this website. See our User Agreement and Privacy Policy. See our Privacy Policy and User Agreement for details. Published on May 26, Colour removal, various chemicals used in ETP.

This chapter elucidates the technologies of biological and chemical wastewater treatment processes. The presented biological wastewater treatment processes include: 1 bioremediation of wastewater that includes aerobic treatment oxidation ponds, aeration lagoons, aerobic bioreactors, activated sludge, percolating or trickling filters, biological filters, rotating biological contactors, biological removal of nutrients and anaerobic treatment anaerobic bioreactors, anaerobic lagoons ; 2 phytoremediation of wastewater that includes constructed wetlands, rhizofiltration, rhizodegradation, phytodegradation, phytoaccumulation, phytotransformation, and hyperaccumulators; and 3 mycoremediation of wastewater. Additionally, this chapter elucidates and illustrates the wastewater treatment plants in terms of plant sizing, plant layout, plant design, and plant location. Wastewater Treatment Engineering. The chapter concerns with wastewater treatment engineering, with focus on the biological and chemical treatment processes.

Every day, millions of cubic metres of wastewater are discharged from homes, businesses, institutions and industries into city sewer systems. Municipal wastewater is one of the largest sources of pollution to surface water in Canada. Before being released to the environment, wastewater needs to be treated. A higher level of wastewater treatment leads to a cleaner effluent and a smaller impact on the environment. The indicators show the level of wastewater treatment provided to the Canadian population. Proportion of population served by municipal wastewater systems, Canada, to

17.3B: Wastewater and Sewage Treatment

Wastewater treatment plant virtual tour

Wastewater is treated in 3 phases: primary solid removal , secondary bacterial decomposition , and tertiary extra filtration. Sewage is generated by residential and industrial establishments. It includes household waste liquid from toilets, baths, showers, kitchens, sinks, and so forth that is disposed of via sewers. In many areas, sewage also includes liquid waste from industry and commerce. The separation and draining of household waste into greywater and blackwater is becoming more common in the developed world. Greywater is water generated from domestic activities such as laundry, dishwashing, and bathing, and can be reused more readily. Blackwater comes from toilets and contains human waste.

Primary treatment removes material that will either float or readily settle out by gravity. It includes the physical processes of screening, comminution, grit removal, and sedimentation. Screens are made of long, closely spaced, narrow metal bars.


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